Hard drive reliability study names names

In November, online backup provider Backblaze published some interesting statistics on hard drive mortality based on over 25,000 units in active service. It found that failure rates were higher in the first 18 months and after three years. Those conclusions matched the findings of other studies on the subject, but frustratingly, they didn't include information on specific makes and models.

And that doesn't even tell the whole story. In Backblaze's storage pods, Seagate's Barracuda 1.5TB has an annual failure rate of over 25%. The 5,400-RPM version of that drive fares better—its failure rate is only 10%—but that's still pretty high compared to the competition. The failure rate of similar Hitachi drives in the same environment is less than 2%.

Only 10% of the hard drives in Backblaze's storage pods come from WD, and they're strictly low-power Green and Red models. The annual failure rates are pretty low, though: only 3-4%. Backblaze's purchasing decisions are largely driven by price, which is probably why fewer WD drives are in the mix. They tend to be a little pricier.

Interestingly, two drives proved to be so unreliable in Backblaze's storage pods that they were left out of the totals completely. Seagate's Barracuda LP 2TB and WD's Green 3TB "start accumulating errors as soon as they are put into production," the company says. It thinks vibration might be part of the problem. Other Barracuda LP and Green models seem unfazed, though.

After three years, only about three quarters of the Seagate drives remain. A surprising number of those failures come between 18 and 24 months, which contradicts the overall trend noted in Backblaze's initial study. Infant mortality seems to be a bigger problem for the WD drives, while the Hitachis fail at a steady but slow rate.

Backblaze says the Seagate drives are also more prone to dropping out of RAID arrays prematurely. The company uses consumer-grade drives that aren't designed explicitly for RAID environments, of course, but that doesn't seem to bother the Hitachis. They spend just 0.01% of their time in so-called "trouble" states, compared to 0.17% for the WD drives and 0.28% for the Seagates.

Overall, Backblaze's data suggests that Seagate drives are less reliable than their peers. That matches my own experiences with a much smaller sample size, and it may influence our future recommendations in the System Guide. Hmm. In the meantime, kudos to Backblaze for not only collecting this data, but also publishing a detailed breakdown.